The enhanced cyclonic activity across southern New Zealand with episodes of stronger than normal westerly or southwesterly winds is expected to continue to influence late summer weather in New Zealand. The moderate El Niño event in the tropical Pacific is expected to last into autumn 2003, and should wane with conditions easing back to neutral by the end of autumn. It should remain weaker than the 1997–98 event. El Niño conditions imply a slightly less than normal risk of a tropical cyclone affecting New Zealand during the late summer.
Temperatures are likely to be near normal over much of the country, and normal or above normal in all eastern areas.
Below average rainfall is expected in the north and east of the North Island, and east of the South Island. Average rainfall is likely elsewhere.
Below normal soil moisture levels and river flows are expected to persist in the north and east of the North Island and the east of the South Island.
A. Climate models give no strong signals about how the climate will evolve, so we assume that there is an equal chance (33%) of the climate occurring in the range of the upper, middle or lower third (tercile) of all previously observed conditions.
B. There is a relatively strong indication by the models (60% chance of occurrence) that conditions will be below average, but, given the variable nature of climate, the chance of average or above-average conditions is also shown (30% and 10% respectively).